The present invention relates to a recording device of the ink-jet type and, particularly, to a nozzle plate for an ink-jet head used for an ink-jet printer, to a method of producing the same and to an ink-jet head using the same. In the ink-jet head of the present invention, a particular ink-repelling layer is formed on the ink blow-out surface of the nozzle plate. Therefore, no ink remains at the ends of the nozzles even after repetitive use, and the ink droplets are permitted to stably fly straight to maintain high printing quality over extended periods of time.
As is well known, an ink-jet printer records characters, figures, patterns and the like on the surface of paper, a film or any other medium by injecting an ink (aqueous ink or nonaqueous ink) through fine nozzles attached to the ends of an ink-jet head, so that the ink droplets fly toward the surface thereof. An aqueous ink is usually used. There can be employed various recording methods depending on the method of forming ink droplets, the method of producing injection energy, etc. For example, the electric charge-controlled recording method uses a piezoelectric element; i.e., a pressure wave is produced in the ink chamber of the head in which the ink is filled by utilizing vibration of the element, thereby to eject the ink by the pressure wave. There have further been known such methods as an electromechanical conversion method, an electro-thermal conversion method, an electrostatic suction method and a discharge method. The ink-jet printer has many merits as indicated by, for example, the facts that (1) printing is accomplished in a non-contacting manner, (2) printing can be effected onto a variety kinds of media, (3) a plain paper can be used to lower the running cost, (4) color printing can be easily accomplished, (5) colors can be vividly reproduced, (6) less noise is produced during the printing, (7) printing can be executed at high speed, etc.
In the ink-jet printer, as will be described later in detail, fine nozzles (usually called xe2x80x9cnozzles for blowing out inkxe2x80x9d or xe2x80x9cink blow-out nozzlesxe2x80x9d) for blowing out the ink have a structure of being formed in a plural number in a nozzle plate, and may be arranged in a single row or in a plurality of rows. The nozzle plate is usually made of a metal material such as a stainless steel or nickel, or a plastic material or ceramic material, and has a thickness of about 0.1 mm, the diameter of the nozzles for blowing out the ink being, generally, from about 30 to about 60 xcexcm.
In order for the ink droplets to be stably blown out straight, in general, the ink must not stay adhered on the nozzle plate near the ink blow-out nozzles and, besides, stability must be improved, in these portions, for the ink. This is because the adhesion of the ink (so-called xe2x80x9cink droplet poolxe2x80x9d) near the ends of the nozzles, grows as the ink oozes out, or the residue of the ink droplets that have flown builds up. Adhesion of the residual ink disturbs the direction in which the ink droplets fly and causes a change in the flying speed, too.
In order to accomplish this object according to the prior art, it has been proposed to form a liquid-repellent or ink-repellent film on the ink blow-out surface of the nozzle plate. As materials that exhibit ink-repelling property, furthermore, there has been known a silicone resin and other fluorine-contained resins. These fluorine-contained resins have a small surface energy and, hence, exhibit excellent resistance against solvents and are hardly wetted by the solutions. The resin of this kind, as a surface-treating agent for the nozzle plate, it can be expected to form a film having an intense ink-repelling property.
According to a prior art for forming a fluorine-contained resin film, a fluorine-contained resin dispersed in a solution is applied by some method onto a substrate and the solvent is vaporized, so that the film of the fluorine-contained resin is melt-formed. In this case, the fluorine-contained resin can be applied by the transfer method, dip-coating method, spin-coating method, roll-coating method, brush-coating method or spray-coating method. Japanese Unexamined Patent Publication (Kokai) No. 2-55140 discloses another method of forming a film of a fluorine-contained resin by relying on the deposition by heat of the fluorine-contained resin.
When the ink-repellent film is to be formed according to the conventional method, long-lasting reliability of the film is important and, particularly, it is important to avoid the deterioration in the ink-repelling property caused by polishing. This is because, the nozzle surfaces are wiped to remove the ink adhered on the nozzle surfaces. However, the ink-repelling property on the nozzle surfaces is deteriorated by the wear resulting from the wiping operation. To avoid deterioration in the ink-repelling property, there can be applied a fluorine-contained resin-containing composite plated film that contains the fluorine-contained resin not only on the surface of the film but also inside the film. The fluorine-contained resin-containing composite plated film is usually formed by depositing a fluorine-contained resin on a substrate by the composite plating that contains the fluorine-contained resin, and by forming the fluorine-contained resin by the heat-treatment. According to this method, the fluorine-contained resin particles are adhered onto the substrate and are then bonded by the heat-treatment. Therefore, a strong film having excellent ink-repelling property is formed compared with only being heat-treated.
Here, a problem arises in that the lower limit in the density of the fluorine-contained resin, distributed on the surface of the fluorine-contained resin-containing composite plated film, varies depending upon the property of the ink that is used. Depending upon the ink, therefore, the distribution of the fluorine-contained resin becomes very dense in the composite plated film. In order to blow out the ink droplets from the nozzles stably and straight, therefore, it becomes necessary to control the density in the distribution of the fluorine-contained resin depending on the ink in the nozzle plate of the ink-jet head.
In the case of the fluorine-contained resin-containing composite plated film, it becomes necessary to adhere the fluorine-contained resin of a predetermined amount onto the surface of the film in order to develop the ink-repelling property on the nozzle surfaces. According to the conventional method, however, the fluorine-contained resin is not adhered in a uniform amount onto the nozzle surfaces, and the ink-repelling property lacks stability from the start.
The ink-repelling property lacks stability from the start on the nozzle surfaces due to the fact that the fluorine-contained resin is adhered in varying amounts onto the nozzle surfaces and, particularly, onto the peripheries of the nozzles. The ink-repelling property on the peripheries of the nozzles is measured as a resistance against the positive pressure. When excellent ink-repelling property is exhibited at the start on the peripheries of the nozzles, the resistance against the positive pressure, which is larger than a predetermined value, is measured. To maintain the ink-repelling property over an extended period of time on the nozzle surfaces, the fluorine-contained resin must be intimately adhered onto the substrate of the nozzle plate on the peripheries of the nozzles and on the nozzle surfaces.
A representative example of the fluorine-contained resin-containing composite plated film will be a fluorine-contained resin-containing nickel composite plating. The fluorine-contained resin-containing nickel composite plating is the one containing, as a matrix, nickel or a nickel alloy that contains fine fluorine-contained resin particles as represented by a polytetrafluoroethylene having a particle diameter of from 0.01 to 100 xcexcm, which has been widely known as plating technology capable of imparting a lubricating property and a releasing property in addition to a water-repelling property.
In forming the water-repelling film, it has been known that the position of meniscus of the ink is determined depending upon the amount of the water-repelling film that has entered into the ink blow-out nozzles to seriously affect the ink blow-out characteristics. That is, when the water-repelling film that has entered is located near the ink blow-out surface, the ink tends to be erroneously blown out due to mechanical vibration from the external side. When the water-repelling film that has entered is located remote from the ink blow-out surface, bubbles are entrapped after the ink droplets are blown out, and the blow-out characteristics lose stability. It therefore becomes necessary to clarify the boundary position between the water-repelling region and the hydrophilic region determined by the amount of the water-repelling film that has entered, in order to make the position of meniscus constant. Here, if represented by the contact angle xcex8 of the ink, the region covered with the water-repelling film is, usually, not smaller than 90 degrees. The material of the nozzle plate is exposed on the region that is not covered with the water-repelling film. In general, the material of the nozzle plate will be a metal such as a stainless steel or nickel, a plastic material such as polysulfone, or silicon or a ceramic. On the surfaces of these materials, the contact angle xcex8 of the ink is roughly not larger than 50 degrees. For the purpose of convenience in this specification, the materials having a contact angle xcex8 of the ink of not smaller than 90 degrees are defined to be water-repellent and the materials having a contact angle xcex8 of the ink of not larger than 50 degrees are defined to be hydrophilic. However, the contact angle xcex8 referred to here may often vary depending on the kind of the solution used for the measurement. In practice, some materials may exhibit the contact angle for the ink of xcex8xe2x89xa690 degrees despite their contact angle for the pure water may be xcex8xe2x89xa790 degrees on an excellent water-repelling surface. This is because, the contact angle xcex8 is determined by the mutual actions among the surface tension of the ink (liquid), interfacial tension between the ink (liquid) and the water-repelling surface (solid), and the surface tension of the water-repelling surface (solid). As generally described, the greater the contact angle xcex8, the better the liquid-repelling property on the surface of the solid material against the liquid. Further, the water-repelling surface having a contact angle for pure water of xcex8xe2x89xa790 degrees, generally, exhibits excellent liquid-repelling property even against the ink.
The position of meniscus determined by the boundary position between the water-repelling region and the hydrophilic region, varies greatly depending on the size of the ink flow path, the thickness of the nozzle plate, the size of the ink blow-out nozzles, the kind of the ink, the driving method and the driving force. Therefore, the boundary position is variable, and a suitable technology is required for mass-producing the nozzle plates.
As a method capable of satisfying such a requirement, Japanese Unexamined Patent Publication (Kokai) No. 7-125220 discloses a method in which a film is partly introduced into the ink blow-out nozzles up to a predetermined boundary position between the water-repelling region and the hydrophilic region, where an optimum position of meniscus is obtained, and the film is cured while bringing a photosensitive resin film into contact with the nozzle plate from the back surfaces of the ink blow-out nozzles with the application of a predetermined temperature and pressure. Thereafter, a fluorine-contained resin-containing nickel composite plating is effected and, finally, the film is removed.
In the case of this method, however, the fluorine-contained resin-containing nickel composite plating must enter into a predetermined position in the ink blow-out nozzles so as to be applied thereto. However, the nozzles in an ordinary nozzle plate have a diameter of about several tens of microns, and it is not easy for the plating solution to enter into the nozzles. This is because the fluorine-contained resin-containing nickel composite plating involves bubbles of a hydrogen gas adhered onto the surface of the to-be-adhered material. Therefore, bubbles adhered near the ink blow-out nozzles prevent the plating solution from entering into the nozzles. In other words, the inner surfaces of the ink blow-out nozzles in a nozzle plate are not coated with the fluorine-contained resin-containing nickel composite plating, or the fluorine-contained resin-containing nickel composite plating does not arrive at the predetermined positions in the nozzles if they are coated. That is, according to the method disclosed in Japanese Unexamined Patent Publication (Kokai) No. 7-125220, the boundary position between the water-repelling region and the hydrophilic region undergoes a variation in each ink blow-out nozzle in a piece of nozzle plate, whereby the blow-out characteristics vary for each nozzle, causing the printing to lose stability, which is a problem that must be solved.
According to the method disclosed in Japanese Unexamined Patent Publication (Kokai) No. 7-125220, there further arises another problem. According to this method, the amount of the photosensitive resin film that enters is controlled by the temperature. It is, therefore, difficult to correctly control the boundary position. When the diameter of the ink blow-out nozzles is decreased in order to improve the printing resolution, furthermore, it becomes very difficult to introduce the photosensitive resin film into the nozzles.
In order to solve the above-mentioned problem, there has been proposed a method which forms a boundary between the water-repelling region and the hydrophilic region in the ink blow-out nozzles by the fluorine-contained resin-containing nickel composite plating by using a positive-type liquid photosensitive resin (so-called xe2x80x9cresistxe2x80x9d) instead of using the photosensitive resin film. According to this method, the nozzle plate is immersed in a positive-type photosensitive resin, the interiors of the ink blow-out nozzles are filled with the positive-type photosensitive resin, the nozzle plate is pulled up, and the ink blow-out surface is coated with the positive-type photosensitive resin by the spin-coating method in a state where the ink blow-out surface is faced upwards. This method uses the positive-type liquid photosensitive resin, and makes it easy to fill the ink blow-out nozzles with the positive-type photosensitive resin. Thereafter, the ink blow-out surface is exposed to ultraviolet rays and is developed. In this case, the intensity of the ultraviolet rays and the exposure time are controlled to correctly control the dissolving amount of the positive-type photosensitive resin, i.e., to correctly control the distance from the ink blow-out surface to where the positive-type photosensitive resin is removed. Since the positive-type photosensitive resin serves as a masking means, it is possible to correctly control the amount of the fluorine-contained resin-containing nickel composite plating flowing into the ink blow-out nozzles so as to be applied thereon.
According to this method, however, though the positive-type photosensitive resin can be applied by the spin-coating method, the thickness of the positive-type photosensitive resin does not necessarily become uniform on the ink blow-out surface; i.e., thickness varies depending upon the places, and the positive-type photosensitive resin film may become locally thick. In particular, the film is thickly formed on the outer periphery of the ink blow-out surface. As a result, even though the ink blow-out surface is exposed to ultraviolet rays and is developed, the positive-type photosensitive resin remains on the ink blow-out surface and, particularly, on the outer periphery thereof. Since the fluorine-contained resin-containing nickel composite plating is not applied onto the positive-type photosensitive resin, this portion becomes a defect in the plated film, and the whole ink blow-out surface is not completely covered with the fluorine-contained resin-containing nickel composite plating. Existence of the defectively plated film permits the ink to easily adhere on the ink blow-out surface, preventing the ink droplets from being stably blown out. Besides, the ink adhered on the ink blow-out surface infiltrates from this defective portion into between the underlying substrate and the fluorine-contained resin-containing nickel composite plating, whereby the underlying substrate is corroded, and the fluorine-contained resin-containing nickel composite plating gradually peels off. Finally, therefore, the ink blow-out surface loses the water-repelling property, and it becomes no longer possible to blow out the ink. This is also a problem that must be solved.
In addition to the above-mentioned problems, the method disclosed in Japanese Unexamined Patent Publication (Kokai) No. 7-125220 involves a further problem. When the fluorine-contained resin-containing nickel composite plating is to be formed according to this method, there exists, on the surface of the plated film, a fluorine-contained resin taken into the metal matrix, a fluorine-contained resin simply adsorbed by the surface, and a fluorine-contained resin eluted out from the film due to firing. Accordingly, though the content of the fluorine-contained resin in the metal matrix is from 5 to 50%, the surface of the film is covered with the fluorine-contained resin at a ratio greater than the above value, and the film exhibits properties of the fluorine-contained resin nearly over the whole surface thereof.
When the fluorine-contained resin-containing composite plating is applied on the surface of the nozzle plate to impart water-repelling property thereto, it becomes necessary to effect the wiping operation to remove the ink adhered on the ink blow-out surface by using a blade of rubber or a similar material. Due to the abrasion resulting from this wiping operation, therefore, the water-repelling film is deteriorated adversely affecting the ink blow-out characteristics. Concretely speaking, when the friction is great between the blade and the film during the wiping operation, the fluorine-contained resin only is abraded on the surface of the fluorine-contained resin-containing composite plated film, whereby the durability is deteriorated, and the fluorine-contained resin is observed in an amount nearly equal to its content in the metal matrix on the surface of the nozzle plate which had been initially covered with the fluorine-contained resin. As a result, the ink droplets adhered on the ink blow-out surface are not removed to a sufficient degree by the wiping operation, and the remaining ink droplets solidify. Besides, the solidified ink droplets form nuclei, and the remaining ink droplets are further solidified spreading to the peripheries of the ink blow-out nozzles. Then, the ink blow-out directions are affected to not only deteriorate the printing quality but also making it difficult to blow out the ink. In practice, therefore, it becomes necessary to select an ink that only weakly adheres onto the surface of the nozzle plate, and to effect the wiping operation under a condition where abrasion to the fluorine-contained resin on the surface is minimized. In practice, therefore, the ink used for the ink-jet head has very limited properties. In order to realize an ink-jet head that features high printing quality, therefore, it becomes necessary to provide a nozzle plate that makes it possible to widen the degree of freedom for selecting the ink and features improved reliability in the maintenance over extended periods of time.
Even when the conventional fluorine-contained resin-containing composite plating, inclusive of the one disclosed in Japanese Unexamined Patent Publication (Kokai) No. 7-125220, is applied onto the ink blow-out surface of the nozzle plate, it is not possible to completely prevent the ink from remaining on the ink blow-out surface. Being affected by the ink remaining on the peripheries of the ink blow-out nozzles, therefore, the direction of blowing out the ink droplets loses stability, the remaining ink coagulates and dries to clog the ink blow-out holes, and the blow out of the ink cannot be continued any longer.
To cope with the adhesion of the ink, the ink-jet printer is equipped with a cleaning mechanism for wiping the ink blow-out surface using a blade made of an elastic rubbery material such as polyurethane rubber as disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 5-201014. When the ink blow-out surface is wiped with this blade many times, however, the water-repelling film is gradually worn out, and the water-repelling property disappears, causing the directions in which the ink droplets are blown out to be changed and making it difficult to normally effect printing in the same way as described above.
It is therefore an object of the present invention to provide a nozzle plate for an ink-jet head which does not permit the ink to stay adhered on the peripheries of the ink blow-out nozzles after the blow out of the ink and enables the ink droplets to be stably blown out straight by solving the above-mentioned various problems inherent in the prior art.
It is another object of the present invention to provide a nozzle plate for an ink-jet head which maintains the ink-repelling property on the nozzle surfaces from the first time and for extended periods of time, enables the ink droplets to be stably blown out straight without permitting the ink to stay adhered on the peripheries of the nozzles or on the nozzle surfaces, maintaining reliability in the printing quality for extended periods of time as a result of stably adhering the fluorine-contained resin on the peripheries of the nozzles and on the nozzle surfaces of the ink-jet head.
It is a further object of the present invention to provide a nozzle plate for an ink-jet head by permitting a fluorine-contained resin-containing nickel composite plating solution to easily infiltrate into the ink blow-out nozzles to keep constant the boundary position between the water-repelling region and the hydrophilic region in the ink blow-out nozzles in a step of applying the fluorine-contained resin-containing nickel composite plating which is a water-repelling film on the ink blow-out surface and in the ink blow-out nozzles of the nozzle plate.
It is a still further object of the present invention to provide a nozzle plate for an ink-jet head in which the boundary position between the water-repelling region and the hydrophilic region remains constant in the ink blow-out nozzles, and the ink blow-out surface is coated with a defect-free fluorine-contained resin-containing nickel composite plating.
It is a yet further object of the present invention to provide a nozzle plate for an ink-jet head maintaining excellent reliability for extended periods of time as a result of improving the durability of the fluorine-contained resin-containing composite plating formed on the ink blow-out surface of the nozzle plate.
It is a further object of the present invention to provide a nozzle plate for an ink-jet head which maintains the water-repelling property at all times and stabilizes the ink blow-out characteristics by suppressing the deterioration in the water-repelling property on the ink blow-out surface.
It is another object of the present invention to provide a nozzle plate for an ink-jet head which features excellent reliability in the maintenance for extended periods of time by concretely demonstrating a method of patterning the fluorine-contained resin-containing composite plating film that facilitates the removal of the ink droplets adhered near the ink blow-out nozzles in the ink blow-out surface of the nozzle plate.
It is an object of the present invention to provide a method of producing the above-mentioned nozzle plate.
It is a still further object of the present invention to provide an ink-jet head which expands the degree of freedom for selecting the ink and realizes excellent printing quality by using the above-mentioned nozzle plate.
The above and other objects of the present invention-will be easily understood from the following detailed description.
According to one aspect of the present invention, there is provided a nozzle plate for an ink-jet head used in an ink-jet type recorder, comprising a flat plate member which defines an ink blow-out surface on one main surface thereof and has a plurality of ink blow-out nozzles penetrating at predetermined positions; wherein
said ink blow-out surface and portions on the inner surfaces of said ink blow-out nozzles neighboring said ink blow-out surface, have, at least partly, an ink-repelling layer of a fluorine-contained resin-containing electrolytic or non-electrolytic composite plating.
In the nozzle plate for the ink-jet printer of the present invention, the ink-repelling layer preferably has a distribution in the content of the fluorine-contained resin.
Preferably, furthermore, the ink-repelling layer has a distribution in the content of the fluorine-contained resin in the direction of thickness of the film, and contains the fluorine-contained resin in large amounts on the surface region.
Preferably, the ink-repelling layer is finely finished on its surfaces in at least the region of said ink blow-out surface. In this case, the ink-repelling layer has a center average surface roughness Ra of, preferably, from 0.02 to 0.1 xcexcm.
It is further desired that the ink-repelling layer has a rugged surface in the region of the ink blow-out surface. It is here desired that the height of ruggedness in the surface of the ink-repelling layer is not smaller than 0.01 xcexcm but is not larger than the thickness of the ink-repelling layer.
Preferably, furthermore, the ink-repelling layer is formed on the ends in the inner surfaces of the ink blow-out nozzles neighboring the ink blow-out surface and on the peripheries surrounding the ink blow-out nozzles on the ink blow-out surface. In this case, it is desired that the ink-repelling layer has a step in the outer peripheries of the nozzles, the step being larger than the thickness of the ink-repelling layer.
In the nozzle plate for the ink-jet head according to the present invention, furthermore, it is desired that the ink-repelling layer has a thickness of at least 2.0 xcexcm.
It is desired that the ink-repelling layer is continuing from the ink blow-out surface to the inner surfaces of the ink blow-out nozzles.
According to another aspect of the present invention, there is provided a method of producing a nozzle plate for an ink-jet head used in an ink-jet type recorder, comprising a flat plate member which defines an ink blow-out surface on one main surface thereof and has a plurality of ink blow-out nozzles penetrating at predetermined positions; wherein the flat plate member is machined to form the ink blow-out nozzles therein at predetermined positions, and an ink-repelling layer of a fluorine-contained resin-containing composite plating is formed at least partly on the ink blow-out surface and on the portions on the inner surfaces of the ink blow-out nozzles neighboring the ink blow-out surface, based on the electrolytic plating method or the non-electrolytic plating method.
In the method of producing a nozzle plate for an ink-jet head according to the present invention, it is desired that the flat plate member is heat-treated at a temperature higher than the melting point of the fluorine-contained resin after the step of plating based on the electrolytic plating method or the non-electrolytic plating method. Preferably, the flat plate member is heat-treated at a temperature higher than the melting point of the fluorine-contained resin by 10 to 50xc2x0 C.
Preferably, furthermore, after the ink blow-out nozzles have been formed by machining in the flat plate member at predetermined positions, the flat plate member is immersed in a plating bath while selectively exposing only those portions where the ink-repelling layer is to be formed, in order to execute the step of plating based on the electrolytic plating method or the non-electrolytic plating method.
Here, the plating bath preferably contains particles of the fluorine-contained resin and a plating metal.
It is desired that ultrasonic waves are applied to the plating bath at least temporarily in the step of plating. In this case, the ultrasonic waves are applied preferably by inserting an ultrasonic wave-generating terminal in the plating bath, or the ultrasonic waves are applied by introducing the plating bath or a container containing the plating bath into a vessel equipped with an ultrasonic wave-generating mechanism.
According to the method of the present invention, the flat plate member is selectively exposed at only those portions on where the ink-repelling layer is to be formed, wherein lithography technology is employed for:
covering predetermined portions of the flat plate member with a photosensitive resist material; and
exposing the resist material to radiations of a predetermined pattern; and wherein
the resist material is removed by developing from either the exposed regions or unexposed regions by utilizing the positive action or the negative action, thereby to selectively expose only those portions on where the ink-repelling layer is to be formed.
Preferably, the step of exposing the resist material is conducted by being divided into the following two steps of:
pre-exposing the flat plate member in the presence of a masking means capable of interrupting the irradiation of radiations on the ink blow-out surface that includes the ink blow-out nozzles, so that the resist material having a relatively large thickness and existing on the outer peripheries of the ink blow-out nozzles is selectively exposed to the pattern of radiations; and
exposing the whole surface of the resist material to the pattern of radiations after the masking means has been removed.
It is further desired that the step for exposing the resist material is conducted while controlling the intensity of the radiations and the exposure time, thereby to adjust the depth of the ink-repelling layer extending into the inner surfaces of the ink blow-out nozzles.
Preferably, the resist material is a positive-type liquid resist material having a viscosity of not larger than 100 cps and is applied onto the surface of the flat plate member by the spin-coating method.
Preferably, the step of plating based on the electrolytic plating method or the non-electrolytic plating method is conducted while controlling the thickness of the plating, so that the ink-repelling layer has a distribution in the content of the fluorine-contained resin in the direction of thickness thereof and that the fluorine-contained resin is contained in large amounts in the surface region.
It is further desired that the ink-repelling layer that is formed is finely finished for its surfaces in at least the region of the ink blow-out surface. In this case, the fine surface finishing is conducted under such a condition that the center surface roughness Ra of the ink-repelling layer lies over a range of from 0.02 to 0.1 xcexcm. It is further desired that the fine surface finishing is effected relying upon at least one working technology selected from the group consisting of mirror-surface grinding, superfinishing, honing, lapping and electrolytic polishing.
It is desired to impart roughness, i.e., recesses and protrusions, to the surface of the ink-repelling layer in the region of the ink blow-out surface. In this case, it is desired that the roughness is imparted under such a condition that the roughness imparted to the surface of the ink-repelling layer has a height of not smaller than 0.01 xcexcm but not larger than the thickness of the ink-repelling layer. In particular, it is desired that the roughness is imparted by machining the surface of the flat plate member on the side of the ink blow-out surface prior to forming the ink-repelling layer.
It is desired that the ink-repelling layer is selectively formed on the end portions in the inner surfaces of the ink blow-out nozzles neighboring the ink blow-out surface and on the outer peripheries of the ink blow-out nozzles in the ink blow-out surface. In this case, it is desired that the ink-repelling layer has a step in the outer peripheries of the nozzles, the step being greater than the thickness of the ink-repelling layer.
According to a further aspect of the present invention, there is provided an ink-jet head used in an ink-jet type recorder, comprising an ink chamber, a nozzle plate of a flat plate member which defines an ink blow-out surface on one main surface thereof and has a plurality of ink blow-out nozzles penetrating at predetermined positions so as to be communicated with said ink chamber, and a pressure generator capable of flying the ink droplets from the nozzles of the nozzle plate toward the recording medium by applying a pressure to the ink in the ink chamber; wherein
the ink blow-out surface and portions on the inner surfaces of the ink blow-out nozzles neighboring the ink blow-out surface, have, at least partly, an ink-repelling layer of a fluorine-contained resin-containing electrolytic or non-electrolytic composite plating.